SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26684e186d55df801221af9421bdc74a8e376e3f0e72affc03f8c04b6657a16f' 
  AND token = 'iDxxNpXkDdSSjZh+0R+kA755UhdeR2tdqb3CLZR2nCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}